Step-induced magnetic-hysteresis anisotropy in ferromagnetic thin films

We investigate the quasistatic magnetic hysteresis of ferromagnetic thin films grown on a vicinal substrate, using Monte Carlo simulations within a two-dimensional XY model. Intrinsic in-plane anisotropy is assigned to surface sites according to their local symmetry. The simulated hysteresis loops show a strong anisotropy: the coercive field is the largest when the external field is along the step direction and vanishes when the external field is perpendicular to the step direction. In general, the coercivity increases with increasing step density, but displays a more complex dependence on film thickness. The simulations also suggest that the mechanism for the magnetization reversal is coherent rotation. These results are in good agreement with experiments.